Thin window cathode-ray tube

ABSTRACT

A thin window cathode-ray tube for recording the emission from a fluorescent material on a recording material placed before a faceplate in high resolution by using a very thin transparent plate as faceplate, in which an adhesive can be prevented to flow into a slit portion by a step structure provided at a junction surface between and envelope and the face.

United States Patent Kaoru Tomii;

Hiroshi Miyama, both of Tokyo, Japan 785,632

Dec. 20, 1968 Nov. 9, I971 Mataushita Electric Industrial Co., Ltd. Osaka, Japan Dec. 28, 1967 Japan Sept. 13, 1968, Japan, No. 43/66410 THIN WINDOW CATIIODE-RAY TUBE 5 Claims, 7 Drawing Figs.

u.s. c1 313/92 11, 220/21 A, 346/110 lI0lj 29/18 Field 61 Search l78/7.85 A, 6.7, 7.4; 220/21 A; 313/74, 92, 89; 346/74 CRT,

Inventors Appl. No. Filed Patented Assignee Priorities [56] References Cited UNITED STATES PATENTS 2,472,988 6/1949 Rosenthal 313/92 2,730,637 1/1956 Atlee 313/74 X Primary ExaminerRaymond F. Hossfeld Attorney-Stevens, Davis, Miller & Mosher ABSTRACT: A thin window cathode-ray tube for recording the emission from a fluorescent material on a recording material placed before a faceplate in high resolution by using a very thin transparent plate as faceplate, in which an adhesive can be prevented to flow into a slit portion by a step structure provided at a junction surface between and envelope and the face.

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INVENTOR KHORU, TONI/ If warm lyfmfl ATTORNEYS PAIENTEUuuv 9 I971 3.619.690

SHEET 2 OF 2 FIG. 5

INVENTOR h'flonu Y TON/l ATTORNEY 5 "ram wmnow CATIIODE-RAY TUBE This invention relates to a thin window cathode-ray tube and more particularly to a thin window cathode-ray tube which uses very thin glass or mica as faceplate and is mainly used for recording.

The face of a conventional thin window cathode-ray tube is constructed by forming a slender rectangular slit 1 at the center of the face of a fiat envelope 2 as shown in FIGS. 1 and 2, then binding a faceplate 6 composed of a thin glass plate or mica plate, a fluorescent material 4 applied on the plate and a film of conductive material formed on the fluorescent material by an adhesive 7 to the envelope face as shown in FIG. 3. This construction maintains the contact between the conductive film 5 of the faceplate and a conductive film 3 which extends from the inner surface of the envelope to the face surface of the envelope and at the same time vacuumtightness of the envelope 2 is obtained.

However, the adhesive 7 sometimes flows into the slit 1 in such a conventional thin window cathode-ray tube: further it is very difi'tcult to apply the adhesive 7 as thin as possible and as near as possible to the slit 1. Therefore it is often not possible to maintain the contact between the conductive film 5 of the faceplate 6 and the conductive film 3 on the inner surface of the envelope and at the same time to obtain the vacuumtightness and resistivity to the atmospheric pressure of the envelope 2.

The width of the slit 1 is required to be very narrow from a viewpoint of strength since the glass or mica of the faceplate 6 is very thin.

One object of the present invention is to provide a thin window cathode-ray tube which can offset such conventional defects as described above, be easily manufactured and is mechanically strong.

Another object of the present invention is to provide a thin window cathode-ray tube in which the envelope and faceplate are bound by an adhesive and there is provided a structure having different steps at least on one side of the junction surface.

The face of the thin window cathode-ray tube according to the present invention is constructed by interposing a glass having a slender slit between the thin transparent plate such as glass plate or mica and the envelope; therefore, the application of a fluorescent material, formation of a metal-back electrode and binding to the envelope can be carried out after the thin transparent plate is bound to the glass having a slender slit. The construction of the device becomes greatly simplified since there is little need to take into account the mechanical strength of the thin transparent plate, and there is no possibility that the fluorescent material will be contaminated by the adhesive since only the binding of the glass to the envelope is required.

This invention will best be understood from the following description when read in conjunction with the accompanying drawings, in which;

FIG. 1 is a view of the face surface of a flat envelope for a conventional thin window cathode-ray tube and FIG. 2 is a sectional view of a portion of the tube;

FIG. 3 is a sectional view of a portion of a thin window cathode-ray tube using a conventional flat envelope;

FIG. 4 is a sectional view of the face surface of a thin window cathode-ray tube of an embodiment according to the present invention;

FIG. 5 is an end view of a thin window cathode-ray tube of another embodiment according to the present invention;

FIG. 6 is a sectional view of the interior of, and in the same plane as, the tube shown in FIG. 5; and

FIG. 7 is a perspective view of a metal fitting used in the thin window cathode-ray tube shown in FIG. 5.

Now. an embodiment of the present invention will be described with reference to the accompanying drawings.

The embodiment shown in FIG. 4 is constructed by forming steps 8 and 9 near a slit 1 at the face surface of an envelope 2, applying an adhesive 7 to a recess 9 and binding a faceplate 6 provided with a fluorescent material 4 and conductive film 5 to the envelope 2. The conductive film 5 provided on th-: faceplate 6 is in contact with the conductive film 3 provided on the inner surface of the envelope 2 at the portion of the step 8 provided at the face of the envelope 2. The adhesive 7 is prevented from flowing into the slit 1 and at the same time a thin window cathode-ray tube having a slit of desired size can be easily manufactured by means of this method.

The structure in which a step is provided on the face surface of the envelope 2 has been described above and it is a matter of course that the same effect can be obtained by a structure having different steps provided on either one of the envelope or the faceplate or on both.

FIGS. 5 and 6 are views illustrating another embodiment of the present invention, in which a slit I2 and projection 13 are provided at the face portion of an envelope II. The reference numeral 14 indicates an inner conductive film provided on the inner surface of the envelope l1; 15 indicates a glass provided with a slender slit 16 having a step 8. An adhesive 18 such as frit is applied to a recess 9 of the glass 15 to bind a faceplate l7 composed of, for example, a thin glass microsheet or mica.

The reference numeral 19 indicates a fluorescent material applied on the inner surface of the faceplate l7 and 20 indicates a metal-back electrode formed by means of, for example, vacuum evaporation of aluminum on a portion of the fluorescent material 19 and undersurface of the glass 15 and on the inner surface of the slit 16.

Reference number 21 designates a frit glass for binding glass 15 and envelop 13; reference numeral 22 designates a metal fitting which forms an electrical conductive path between inner conductive film l4 and metal-back electrode 20. Fitting 22 has opposed supporting projections 23 in contact with conductive film l4 and a contact portion 24 at the center which makes contact with metal-back electrode 20 on the inner surface of the glass 15. The center limb of metal fitting 22 and contact portion 24 form a I-shape, as seen in FIG. 6. The length of contact portion 24 is made slightly larger than the width of groove 16 and the height of said center limb is so selected that the metal fitting 22 electrically connects electrode 20 and conductor film 14 with the center limb sightly bent so as to maintain a pressure contact between film 14 and fitting 22 and between electrode 20 and fitting 22. Two such metal fittings are employed in the preferred embodiment of this invention, provided one at each end of groove 16.

The thin window cathode-ray tube of the present invention is constructed as follows: first the glass microsheet I7 is bound to the glass 15 and the fluorescent material 19 is applied; then the metal-back electrode 20 is formed; and next the glass 15 is bound by the frit glass 21 to the envelope 1]. The inner conductive film 14 is kept in contact with the metal-back electrode 20 by means of the elastic metal fitting 22.

What is claimed is:

l. A thin window cathode-ray tube, comprising: a conductive film disposed on the inner surface of said tube; the front surface of said tube having a slit defined therein and a projection substantially surrounding said slit; a relatively thin faceplate; a glass plate, having a slit defined therein coincident with said slit defined in said tube, disposed on said front surface of said tube between said faceplate and said projection; said glass plate having a stepped portion on its surface confronting said faceplate; said glass plate having a recessed portion containing an adhesive material for securing said faceplate to said glass plate; and a fluorescent material and a metal-back electrode electrically connected to said conductive film disposed on a portion of the inner surface of said faceplate exposed to the inside of said tube through the slit in said glass plate.

2. A thin window cathode-ray tube according to claim I, wherein said metal-back electrode is formed on said fluorescent material and further comprising means, including at least one metal fitting, electrically connecting said conductive film and said metal-back electrode.

wherein said second and third portions have a T-shaped cross section, and said second portion is dimensionally larger than the width of the slit defined in said glass plate to form a press fit with said back electrode.

5. A thin window cathode-ray tube according to claim 2, wherein said metal fitting is elastic. 

1. A thin window cathode-ray tube, comPrising: a conductive film disposed on the inner surface of said tube; the front surface of said tube having a slit defined therein and a projection substantially surrounding said slit; a relatively thin faceplate; a glass plate, having a slit defined therein coincident with said slit defined in said tube, disposed on said front surface of said tube between said faceplate and said projection; said glass plate having a stepped portion on its surface confronting said faceplate; said glass plate having a recessed portion containing an adhesive material for securing said faceplate to said glass plate; and a fluorescent material and a metal-back electrode electrically connected to said conductive film disposed on a portion of the inner surface of said faceplate exposed to the inside of said tube through the slit in said glass plate.
 2. A thin window cathode-ray tube according to claim 1, wherein said metal-back electrode is formed on said fluorescent material and further comprising means, including at least one metal fitting, electrically connecting said conductive film and said metal-back electrode.
 3. A thin window cathode-ray tube according to claim 2, wherein said at least one metal fitting comprises: a first portion disposed in the slit defined in said tube surface and contacting said inner conductive film; a second portion disposed adjacent the slit defined in said glass plate and contacting said back electrode; and a third portion electrically connecting said first and second portions.
 4. A thin window cathode-ray tube according to claim 3, wherein said second and third portions have a T-shaped cross section, and said second portion is dimensionally larger than the width of the slit defined in said glass plate to form a press fit with said back electrode.
 5. A thin window cathode-ray tube according to claim 2, wherein said metal fitting is elastic. 